1. Field of the Invention
The present invention concerns a method of conveying with a particular longitudinal spacing p products arriving in a particular longitudinal direction and at least on average at a particular rate c, the method consisting in having the products rest on first conveyor surfaces in succession in that direction and moving in that direction at a particular speed V.sub.1 equal to the product of the particular rate c by the particular spacing p. It also concerns a device for conveying products arriving at least on average at a particular rate c in a particular longitudinal direction with a particular longitudinal spacing p, the device including first conveyor surfaces in succession in that direction, means for moving the first conveyor surfaces in that direction at a particular speed V.sub.1 equal to the product of the particular rate c by the particular spacing p and means for placing the products on the most upstream first conveyor surface, with reference to that direction, at least on average at the particular rate c.
In the present context "product" refers either to an individual object such as a cake or a cheese whose transportation by the method of the invention and/or by means of the device of the invention constitutes a preliminary step before individual packaging or a group, whether organized or not, of individual objects whose transportation constitutes a preliminary step before collective packaging, such as chocolates to be packaged in rows in a common box or sweets adapted to be packaged loose in a common sachet. It is to be understood that the above examples are in no way limiting on possible applications of the method and device in accordance with the invention. In particular, the method and device in accordance with the invention apply equally to non-food products such as tools, hardware or knick-knacks, hygiene or other items, and to the orderly transportation of food or non-food products for forms of processing other than packaging.
2. Description of the Prior Art
Many forms of automatic processing of large numbers of products, such as individual or collective packaging processes, require the products to be presented in a precisely ordered manner.
In particular, products fed to automatic packaging machines, for example, must conform as accurately as possible to a particular spacing referred to a particular direction of movement towards the packaging machine, and if several rows of products are fed in this direction to be packaged simultaneously, whether collectively or individually, it may be essential not only for the products in each row to be at the same spacing but also for the products in the different rows to arrive at the packaging station in phase or with a particular phase difference.
Two techniques are currently available for setting products at a particular spacing or assuring that they retain a particular spacing and/or for setting adjoining rows of products in phase or with a particular phase relationship.
One of the above techniques consists in lowering onto one of the first conveyor surfaces barriers against which the products strike and which are raised sequentially to release simultaneously all the products that have struck a barrier during a particular time period. This solution is compatible only with hard products, i.e. when there is no risk of the products being damaged by striking the barriers. It necessitates fast lowering and raising of the barriers and thus requires rugged and therefore costly mechanical resources to assure these movements. Its operation also generates a high level of noise. Finally, it is important to prevent a barrier being lowered onto a product and it is therefore necessary to provide electronic means for sensing the presence of products, in order to prevent such accidents, and to increase the number of barriers so that a product escaping from one is nevertheless stopped and then released at a time at which it occupies a particular position relative to the other products, which complicates the device and makes it even more costly in that it is of course necessary to provide the same ruggedness and to take the same precautions against a barrier encountering a product while it is being lowered for all the barriers.
Another prior art solution consists in moving the products along successions of individual conveyor surfaces whose speeds are individually controlled by sensing the relative positions of the products using appropriate sensors. This solution can be applied to a wider range of products in that it is compatible with soft products and a device using it is much quieter than a device using the other prior art solution previously commented on. However, sensing the relative positions of the products and controlling the individual conveyor surfaces leads to great complexity of the mechanical equipment driving the conveyor surfaces and the electronic control equipment, making this a particularly costly solution.